The present invention is directed to rollers or cylinders with a metallic foam core, and to a process for producing these rollers or cylinders.
Processes for producing a metallic foam have become known from U.S. Pat. No. 3,087,807 A and DE 40 18 360 C1. U.S. Pat. No. 3,087,807 A discloses that a hollow body can be filled with a metallic foam by generating the metallic foam inside the hollow body.
DE 44 43 840 C2 shows an impact protector for a motor vehicle paneling element. In this case, a cushion made of a light metal foam is completely enclosed in a casing. This document does not show whether or how the light metal foam may be fastened in the interior of the casing.
A way of producing plates in sandwich construction can be taken from DE-OS 21 19 490. Metallic foam plates arranged between cover plates are used. The cover plates are fastened on the metallic foam plate.
Rotating cylinders which are useable, for example, in the form of paper guide rollers, or hollow cylinders which are useable, for example, as printing cylinders or as rubber blanket cylinders, are known in connection with rotary printing presses, for example. Paper guide rollers, for example, are driven by the web itself, which is to be guided by them. This can result in an unintended effect imparted to the print carrier web, which web may be, for example, a paper web or a foil web since, as stated, the energy for accelerating or braking the cylinders or rollers must be applied to the cylinders or rollers themselves via the print carrier web. Added to this are the difficulties that result because, on the one hand, the paper web widths continue to become greater (for example 3.80 m) and, on the other hand, the speeds of the print carrier webs are also continuously increased and have currently reached 18 m/sec.
It is the object of the present invention to provide rollers and cylinders with metallic foam cores for use as rollers and cylinders intended for rotating operation, and to provide a process for producing these rollers and cylinders.
In accordance with the present invention, this object is attained by the production of a metallic foam core separate from a roller or cylinder which has a hollow casing. The separately formed metallic foam core is inserted into the interior of the hollow casing and is fastened, in a force-transmitting manner, to the interior surface of the casing.
The advantages to be gained by the present invention reside, in particular, in that rollers, cylinders, or the like, which are suitable for rotary operations at high speeds of revolutions, and having a metallic foam core, can be created. These rollers or cylinders have a casing which is not stressed by the high temperatures, for example in the area of 500 C required for creating a metallic foam. It is possible to join different metals, for example to join rollers made of steel with an aluminum foam, so that there is no relative movement between the interior surface of the roller and the metallic foam surface occurring in the course of rotary operations of the rollers or cylinders during acceleration and braking. It is therefore possible to utilize all of the advantages provided by filling the rollers or cylinders with a metallic foam, without it being necessary to overstress the rollers or cylinders thermally.
Thus it is possible, for example, to omit an individual electric motor drive, for example, for the paper guide rollers.